American Kathryn Mayorga has accused Ronaldo of sexually assaulting her in a hotel in Las Vegas in 2009, with the Portugal captain having come out to “firmly deny” the claims.

German publication Der Spiegel first reported the accusations, which also included the suggestion Ronaldo paid Mayorga $375,000 in 2010 as part of a privacy agreement, preventing her from going public with the allegations.

Mayorga filed a lawsuit in an attempt to quash that agreement while Las Vegas police have re-opened an investigation.

On Thursday, the Wall Street Journal first reported that police in Las Vegas police had requested a sample of Ronaldo's DNA, citing “a law-enforcement official with knowledge of the case.” The report also claims that a warrant was recently sent to the court system in Italy.

Christiansen has previously confirmed that the payment was made to Mayorga, but said documents presented as evidence had been "stolen" and "completely fabricated."

"To be clear, Mr. Ronaldo vehemently denies all of the allegations in the complaint and has consistently maintained that denial for the last nine years,” Christiansen said in a statement in October.

"The documents which purportedly contain statements by Mr Ronaldo and have been reported in the media are complete fabrications. It is my understanding that in 2015, dozens of entities [including law firms] across many different industries throughout Europe were hacked and their electronic data was stolen and captured by a cyber criminal.

"This hacker attempted to sell this data, and one media outlet has now irresponsibly published the stolen documents, significant portions of which were altered and/or completely fabricated. To absolve any doubt, Mr Ronaldo has always maintained, as he does today, that what occurred in 2009 in Las Vegas was consensual in nature.

"While Mr. Ronaldo does not deny the existence of the mutual agreement and release, his motivations for agreeing to that resolution have been twisted to say the least.

"Far from any admission of guilt or any ulterior motive, Mr Ronaldo was advised to privately resolve the allegations against him in order to avoid the inevitable attempts that are now being made to destroy a reputation that has been built upon hard work, athleticism and honor.

"Unfortunately, he now finds himself embroiled in the type of litigation that is all too commonplace in America."

Furthermore, following the report that a DNA sample has been requested, Christiansen gave a statement to Omnisport, saying: "Mr. Ronaldo has always maintained, as he does today, that what occurred in Las Vegas in 2009 was consensual in nature.

"So it is not surprising that DNA would be present, nor that the police would make this very standard request as part of their investigation."

Ronaldo, 33, has scored a league-high 14 goals in Serie A and 15 in all competitions for Italian champions Juve this season, having arrived from Real Madrid in July.